Aeroplane phonograph reproducer



Dec. 30, 1930. J. M. COBURN 9 3 AEROPLANE PHONOGRAPH REPRODUCER Filed Sept. 7, 1927 2 Sheets-Sheet l INVENTOR M--- w M I I wrrugsszs Dec. 30, 1930. J. M. COBURN AEROPLANE PHONOGRAPH REPRODUCEB Filed Sept. v, 1927 Sheets-Sheet 2 um WM wnmebsas 1 WM Patented Dec. so, 1930 PATENT errier,

. JAMES M. confirm,- or KANSAS CITY, nrssounrhssreuon TO PLANE-SPEAKER con- PORATION, OF NEW YORK, N. .Y.,

A CORPORATION OF DELAWARE AEnorLANErHoNoeRArH anrnonuonn f llpplication filed September 7,1927. Serial No. 218,012.

This invention relates to aeroplanes, balloons, dirigibles, and other aerial navigating means, which will herein bedesignated generally as aeroplanes, and it has to'doparticularly with means for reproducing and amplifying messages to be'broadcast therefrom.

The general object of this invention'is to provide means for broadcasting from an aeroplane, by whichextrane'ous noises from.

the motor, propeller or other sources will be substantially excluded from the amplifying system, thereby removing one cause of over- I loading of the amplifier and distortion of the sound produced.

" An objectis to make useof phonographic reproducing means for supplying impulses to an amplifying system'carried by an aeroplane, and to construct the reproducing means so that it may be adjusted so as not to be affected by movements of the'aeroplane, A further object is to provide a sturdy, readily constructed unit foriuse with the phonographic reproducer which afiords positive and non-varying operation thereof independent of changes in gravity, centrifugal,

centripetal, or other forces exerted during.

' operation of the aeroplane, whereby normal and uniform reproduction is made possible. Loud speakers and amplifying units have been heretofore'provided on aeroplanes, for

the purpose of broadcasting messages, or for advertis ng purposes. These have made use of microphones lnto whlch the announcer 7 spoke; and while they have attained consid-' erable success, certain disadvantages were inherent in them. Among these are chiefly the overloading of the amplifying system by thenoises ofthe motor andpropeller, and

0 distortion of the sound produced. The preS-' 4 I cut inventlon provldesmeans for overcoming these disadvantages, and also makes it possibleto use records prepared in advance,

' either or, an advertising nature, or comprising speeches, news, music or other desired 5 material, whereby the record is reproduced faithfully, and with no delays such as ma occur in oral broadcasting. f

One embodiment of the invention is illustrated in the accompanying drawings, of

which Fig. 1 represents a plan'view of the reproducing unit; Fig. 2 a side elevation of the device shown in Fig. 1; Fig; 3 a side elevation of the "coupling shown in Fig. 2-;Fig. 4 a view, partly in section, of the reproducer. and. carriage taken on line IVIV of Fig. 2; and Figs. 5 and 6 schematic representations of two means of converting the mechanical impulses produced by the ireproducer to electrical impulses capable of successful treatment in the amplifieicfl adapting a phonograph reproducer for use in an aeroplane,the weight of the reproducer and associated mechanism creates special problems because of the inertia forces produced inoperation of the craft. For ex ample, if the aeroplane suddenly goes upor down. the needle pressure increases or decreases,-producing a variation in the impulses conveyed to the reproducer. 1 j p Also, side movements of the aeroplane, as in banking, set .up centrifugal or similar forces which will tend to press the needle against one side of the grooves, which will vary the impulses set up inlthe needle, and theside pressure may even become great enough to slow upthe reco'rd, or to force the needle out of a groove.

7 Special features of the'invention'comprise the use with an aeroplane equipped with audio broadcasting apparatus, of a phonograph reproducer pivotedhorizontally about its center of gravity and adapted to be resiliently urged vertically against the record to produce a un form pressure regardless of movements of theaeroplane. In order further to create uniform operation 1 unaffected by changes in directionorspeedof the aeroplane, a special frame is provided on which the reproducer is rigidly supported and driven uniformly over there'cord. The reproducer is designed to converttheimpulses received from the record to electrical impulses, so that only the desired impulses aresupplied to an amplifying sys tem carriedby' the aeroplane.

Referring to the drawings, the frame mechlyf mounted on a screw-driven carriage '2, 111 ch supporte'dby and driven on a pair of rails '3 and 3a by means ofa fixed screw 4.

- anism' comprises a reproducer head 1, pivotal- ,The rails are rigidly secured by nuts 5 on to notches formed in the base, so that end movement is prevented and the supporting frame can be'raised when desired. Side movement of the frame is preventedby pins 11 and 11a provided in the base plates and adapted to engage corresponding holes in the end supports. Intermediate the rails and rotatably supported in the end supports is a screw member l, driven: by a bevel gear 12 mounted thereon and secured thereto by a pin or screw 12a. Gear 12 meshes with and is actuated by a bevel pinion gear 13, rotatably supported by a cross brace 14 mounted in fixed position on the rails, The shaft-driving gear 13 is operatively connected to the spindle 15 of a phonograph turntable 16 through a coupling 17.

As shown in Figs. 2 and 3 this coupling is counter-bored to receive the spindle, and a pin 18 is horizontally disposed in the center of thebore, to engage a slot 19 cutinthe spindle, thus permitting easy disengagement of the coupling when the supporting frame is raised on hinges 9. i v r r A special feature of the invention comprises mounting the reproducer head so as to be unaffected by any change in the'inertia forces. This is accomplished by the horizontal pivotal support shownrin Figs. 2 and 4:. The reproducer headl is constructed to be supported on horizontal pivots 20 and 20a whose axis passes through'its' center of-gravity, and which are held-in adjustable bearing screws 21 and 21a, accurately threaded in a fork suspension .member 22, the outer ends of. the screws being secured by bolts 23 and 23a. Suspension member 22 is secured tojcarriage 2; by a .bolt24, appropriate nuts and washers or spacing members being used. In order to cause the needle 25 to exert a'consta-nt 7 pressure on record placed therebelow, a

spring tension device is employed, which, act

- ingwith the torqueless pivoting creates a constant pressure regardless of change in the upward or downward forces. This device comprises apin 26, adapted to bear onthe needle end of the reproducer head. Interposed betweenpin 26 anda screw 27 is a spring 28,

the tension'of which can be varied by varying the setting of the screw, and which for any particular setting exerts'a constant thrust .on the pin, pressing the needle with-constant pressure into the grooves in the record, the pressure not being varied by movements in a vertical plane.

c fThe' reproduce-r maylbe'adapted for use inaudio amplification in a number of ways, two of .WhlCll are d agrammatically shown in Figs. 5. an'd6/ In generalthese methods depend upon the production of electrical impulses varying in intensity with the vibrations of the needle, caused by the impressions in the record. In Fig. 5 the needle 25a follows the grooves in a record mounted on and rotated by turntable 16a. Operatively connected withthe needle 25a and adapted to respond to the slight variations in impulses created in the needle is a vibration transmittingdevice 30, adapted to vary the pressure on a diaphragm 31 mounted in a resistance box 32. This box is filled with granular carbon, and connected with it is pair. of wires 33 and 34, and battery 35. This device is in principlesubstantially that of the ordinary telephone transmitter,

and requires no extended description other than to state that the resistance to the elecrical flow of the battery current through the graphite varies with the pressure applied thereto, and consequently variable electrical impulses are created in response to the varying pressures of the needle, which are conveyed. to an amplifying system, not shown, and there converted to audio-frequency and amplified as may be desired.

Fig. 6 shows amodification, in which needle25b is'mounted for axial movement between a pair of magnets 36and37, and surrounding it is a helix 38 electrically connected to lead wires 39 and 40, a battery 41 being cut intov the circuit. Variations of the record groove cause the needle to .move inLand out of the magnet fields within the helix, thus varying thecurrents in the electrical circuit in such manner that impulses are set up which when passed through a suitable amplifying system. as before, reproduce the sounds recorded on the record.

Tooperate this device, latches 10 are released, permitting the framework, drive mechanism and reproducer. to be raised, when a record isplaced on the. turntable, and then the reproducer carriage to move over the record, the gear ratio and pitch of the screw being selected to drive the'reproducer at the proper rate, i.' e. to move the carriage the width of one groove for 'eaclrrevolution of the record' During thisoperation the impressions in the record will create'vibrational'movements of the needle, which in turn are converted to electrical impulses and amplified and the speech, music, advertising or other material on; the recor'd transmitted from a suitable loudfspeakersystem carried by theaeroplane; x H

1 The useiofthis principle of reproduction.

permits broadcasting with none of the interference normally created by the aeroplane itself, inasmuch as no sounds are transmittedto the amplifier, which receives only the positively produced impulses from the record. Furthermore, truereproduction is assured, since the repro-ducer is rigidly mounted toprevent any lateral movement created by banking or side components ofthe aeroplane operation, and because the.

ducer-supporting means coacting with said frame to uniformly move the reproducer over a record while maintaining constant needle pressure irrespective of movements of the aeroplane; I

2. A reproducing mechanism for use with an aeroplane broadcasting apparatus includ- ,ing a power amplifier,-adapted to deliver to v the amplifier onlythose impulses which it is desired to broadcast and which is not affected by movements of the aeroplane, comprising a supporting frame, a power-actuated screw mountedtherein, a carriage mounted I on said frame and actuated by said screw,

phonograph reproducing mechanism mounted pivotally about its center of gravity on said carriage and operatively connected to the amplifier,- phonograph turntable, mechanism, and means associated with said turntable mechanism for actuating said screw po- 7 sitively to move the carriage and reproducer progresslvely over a record. 7

3.. A reproducing-mechanism for use with 1 an aeroplane broadcasting apparatus including a power amplifier, adapted to deliver to the amplifier only those'impulses which it is desired to broadcast and which is not affected by movements of theaeroplane, comprising a supporting frame, a power-actuated screw mountedtherein, acarriage mounted thereon and actuated by said screw,phonograph reproducing mechanism pivotally connected about its center of gravity to said car- I riage, phonograph turntable mechanism,

gears associated with said turntable mechanism and said screw to move the carriage and reproducer progressively over a record, and means associated with sa1d ,reproducer to convert the impulses created therein by the impressions on the record to corresponding electric impulses, and to transmit them to v the amplifier.

4. A reproducingmechanism for use with an aeroplane broadcasting apparatus including a power amplifier, adapted to deliver to the amplifier only-those impulses which it is desired'to broadcast and which is not afli'ected by movementsof the aeroplane, comprising a supporting frame, a power-actuated screw mounted therein, a carriage mounted thereon and actuated vby said screw, phonograph reproducing mechanism pivotally connected about its center of gravity to said carriage, phonograph turntable mechanism, adjustable means cooperating between the carriage and reproducer to uniformly and constantly press the reproducer needle on a record, and means associated with said reproducer to connect the impulses created therein by the impressions on the recordto corresponding electric impulses, and to transmit them to the amplifier. V

In testimony whereof, I signmy name. 

